Months after a senior Japanese International Atomic Energy Agency official urged better safety procedures at nuclear plants around the world to "avoid another Chernobyl," another IAEA official said that earthquakes presented a "serious problem" to nuclear plant safety, according to a recently released U.S. State Department cable.

The official, who is only identified as "the IAEA presenter" at the 2008 G8 Nuclear Safety and Security Group meeting, said that some recent earthquakes "exceeded the design basis for some nuclear plants" and complained that safety guides for such plants had only been revised three times in more than three decades. The IAEA had sent officials to Japan in late 2008 to study the effects of an earthquake on some reactors, said the cable, which was posted on the website of the British newspaper The Telegraph.

"This is a serious problem that is now driving seismic safety work," the official said.

The presenter's comments came after the senior Japanese official at the IAEA, Tomihiro Taniguchi, urged the international community the same year to observe stricter safety standards to "avoid another Chernobyl," as reported in a separate cable.

Other leaked U.S. State Department documents, published by the website WikiLeaks, show the U.S. had little confidence in Taniguchi, who was at the time the head of the IAEA's Department of Nuclear Safety and Security.

"Taniguchi has been a weak manager and advocate, particularly with respect to confronting Japan's own safety practices, and he is a particular disappointment to the United States for his unloved-step-child treatment of the Office of Nuclear Security," said the 2009 document, posted on the website of the British newspaper The Guardian. "This position requires a good manager and leader who is technically qualified in both safety and security."

Before joining the IAEA in 2001, Taniguchi was the executive director of Japan's Nuclear Power Engineering Corporation, a company that specifically dealt with nuclear plant security in the aftermath of earthquakes. Taniguchi stepped down from the IAEA after another Japanese official, Yukiya Amano, assumed control of the agency as Director General in September 2009.

Amano, now the sole representative from Japan on the senior IAEA management team, is scheduled to speak in April about the safety improvements made since that incident at an international conference called "Chernobyl, 25 Years On: Safety for the Future."

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Japan's 3-Step Plan for Nuclear Safety

In the same 2008 meeting in which Taniguchi pushed for more international safeguards when it comes to nuclear power, other IAEA officials "saw promise in the Japanese 3S's (Safety, Security, Safeguards) proposal," the leaked State Department document said.

That proposal, as described in a 2010 document from the Japan Atomic Energy Agency obtained by ABC News, is a highly technical how-to on nuclear facility safety -- from the safe operation of nuclear facilities in crisis, to the protection of the actual nuclear materials and guards against proliferation.

CLICK HERE to read a PDF version of "Nuclear Data in Safety and Security" from the JAEA.

Even with the 3 S's system, Japan appeared overwhelmed by the March 11 quake, according to Tony Pietrangelo, a spokesman for lobbying group Nuclear Energy Institute.

"Clearly what happened in Japan is well beyond what [the nuclear plants] were designed for," he said.

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ABC News' David Kerley and Cindy E. Rodriguez contributed to this report.